# Python implementation of the MySQL client-server protocol
#   http://forge.mysql.com/wiki/MySQL_Internals_ClientServer_Protocol

import re

try:
    import hashlib
    sha_new = lambda *args, **kwargs: hashlib.new("sha1", *args, **kwargs)
except ImportError:
    import sha
    sha_new = sha.new

try:
    import ssl
    have_ssl = True
except ImportError:
    have_ssl = False

import socket
import struct
import sys
import os
import ConfigParser

try:
    import cStringIO as StringIO
except ImportError:
    import StringIO

from charset import MBLENGTH
from cursors import Cursor
from constants import FIELD_TYPE
from constants import SERVER_STATUS
from constants.CLIENT import *
from constants.COMMAND import *
from converters import escape_item, encoders, decoders, field_decoders
from err import raise_mysql_exception, Warning, Error, \
     InterfaceError, DataError, DatabaseError, OperationalError, \
     IntegrityError, InternalError, NotSupportedError, ProgrammingError

DEBUG = False

NULL_COLUMN = 251
UNSIGNED_CHAR_COLUMN = 251
UNSIGNED_SHORT_COLUMN = 252
UNSIGNED_INT24_COLUMN = 253
UNSIGNED_INT64_COLUMN = 254
UNSIGNED_CHAR_LENGTH = 1
UNSIGNED_SHORT_LENGTH = 2
UNSIGNED_INT24_LENGTH = 3
UNSIGNED_INT64_LENGTH = 8

DEFAULT_CHARSET = 'latin1'
BUFFER_SIZE = 256*256*256-1

def dump_packet(data):
    
    def is_ascii(data):
        if data.isalnum():
            return data
        return '.'
    print "packet length %d" % len(data)
    print "method call[1]: %s" % sys._getframe(1).f_code.co_name
    print "method call[2]: %s" % sys._getframe(2).f_code.co_name
    print "method call[3]: %s" % sys._getframe(3).f_code.co_name
    print "method call[4]: %s" % sys._getframe(4).f_code.co_name
    print "method call[5]: %s" % sys._getframe(5).f_code.co_name
    print "-" * 88
    dump_data = [data[i:i+16] for i in xrange(len(data)) if i%16 == 0]
    for d in dump_data:
        print ' '.join(map(lambda x:"%02X" % ord(x), d)) + \
                '   ' * (16 - len(d)) + ' ' * 2 + ' '.join(map(lambda x:"%s" % is_ascii(x), d))
    print "-" * 88
    print ""

def _scramble(password, message):
    if password == None or len(password) == 0:
        return '\0'
    if DEBUG: print 'password=' + password
    stage1 = sha_new(password).digest()
    stage2 = sha_new(stage1).digest()
    s = sha_new()
    s.update(message)
    s.update(stage2)
    result = s.digest()
    return _my_crypt(result, stage1)

def _my_crypt(message1, message2):
    length = len(message1)
    result = struct.pack('B', length)
    for i in xrange(length):
        x = (struct.unpack('B', message1[i:i+1])[0] ^ struct.unpack('B', message2[i:i+1])[0])
        result += struct.pack('B', x)
    return result

# old_passwords support ported from libmysql/password.c
# note: the following functions do not work! they are very close, though.
SCRAMBLE_LENGTH_323 = 8

class RandStruct_323(object):
    def __init__(self, seed1, seed2):
        self.max_value = 0x3FFFFFFFL
        self.seed1 = seed1 % self.max_value
        self.seed2 = seed2 % self.max_value

    def my_rnd(self):
        self.seed1 = (self.seed1 * 3L + self.seed2) % self.max_value
        self.seed2 = (self.seed1 + self.seed2 + 33L) % self.max_value
        return float(self.seed1) / float(self.max_value)

def _scramble_323(password, message):
    hash_pass = _hash_password_323(password)
    hash_message = _hash_password_323(message[:SCRAMBLE_LENGTH_323])
    hash_pass_n = struct.unpack(">LL", hash_pass)
    hash_message_n = struct.unpack(">LL", hash_message)

    rand_st = RandStruct_323(hash_pass_n[0] ^ hash_message_n[0],
                             hash_pass_n[1] ^ hash_message_n[1])
    outbuf = StringIO.StringIO()
    for _ in xrange(min(SCRAMBLE_LENGTH_323, len(message))):
        outbuf.write(chr(int(rand_st.my_rnd() * 31) + 64))
    extra = chr(int(rand_st.my_rnd() * 31))
    out = outbuf.getvalue()
    outbuf = StringIO.StringIO()
    for c in out:
        outbuf.write(chr(ord(c) ^ ord(extra)))
    return outbuf.getvalue()

def _hash_password_323(password):
    nr = 1345345333L
    add = 7L
    nr2 = 0x12345671L

    for c in [ord(x) for x in password if x not in (' ', '\t')]:
        nr^= (((nr & 63)+add)*c)+ (nr << 8) & 0xFFFFFFFF
        nr2= (nr2 + ((nr2 << 8) ^ nr)) & 0xFFFFFFFF
        add= (add + c) & 0xFFFFFFFF

    r1 = nr & ((1L << 31) - 1L) # kill sign bits
    r2 = nr2 & ((1L << 31) - 1L)

    # pack
    return struct.pack(">LL", r1, r2)

def pack_int24(n):
    return struct.pack('BBB', n&0xFF, (n>>8)&0xFF, (n>>16)&0xFF)

def unpack_uint16(n):
  return struct.unpack('<H', n[0:2])[0]


# TODO: stop using bit-shifting in these functions...
# TODO: rename to "uint" to make it clear they're unsigned...
def unpack_int24(n):
    return struct.unpack('B',n[0])[0] + (struct.unpack('B', n[1])[0] << 8) +\
        (struct.unpack('B',n[2])[0] << 16)

def unpack_int32(n):
    return struct.unpack('B',n[0])[0] + (struct.unpack('B', n[1])[0] << 8) +\
        (struct.unpack('B',n[2])[0] << 16) + (struct.unpack('B', n[3])[0] << 24)

def unpack_int64(n):
    return struct.unpack('B',n[0])[0] + (struct.unpack('B', n[1])[0]<<8) +\
    (struct.unpack('B',n[2])[0] << 16) + (struct.unpack('B',n[3])[0]<<24)+\
    (struct.unpack('B',n[4])[0] << 32) + (struct.unpack('B',n[5])[0]<<40)+\
    (struct.unpack('B',n[6])[0] << 48) + (struct.unpack('B',n[7])[0]<<56)

def defaulterrorhandler(connection, cursor, errorclass, errorvalue):
    raise
    err = errorclass, errorvalue
    
    if cursor:
        cursor.messages.append(err)
    else:
        connection.messages.append(err)
    del cursor
    del connection

    if not issubclass(errorclass, Error):
        raise Error(errorclass, errorvalue)
    else:
        raise errorclass, errorvalue


class MysqlPacket(object):
  """Representation of a MySQL response packet.  Reads in the packet
  from the network socket, removes packet header and provides an interface
  for reading/parsing the packet results."""

  def __init__(self, socket):
    self.__position = 0
    self.__recv_packet(socket)
    del socket

  def __recv_packet(self, socket):
    """Parse the packet header and read entire packet payload into buffer."""
    packet_header = socket.recv(4)
    while len(packet_header) < 4:
        d = socket.recv(4 - len(packet_header))
        if len(d) == 0:
            raise OperationalError(2013, "Lost connection to MySQL server during query")
        packet_header += d

    if DEBUG: dump_packet(packet_header)
    packet_length_bin = packet_header[:3]
    self.__packet_number = ord(packet_header[3])
    # TODO: check packet_num is correct (+1 from last packet)

    bin_length = packet_length_bin + '\000'  # pad little-endian number
    bytes_to_read = struct.unpack('<I', bin_length)[0]

    payload_buff = []  # this is faster than cStringIO
    while bytes_to_read > 0:
      recv_data = socket.recv(bytes_to_read)
      if len(recv_data) == 0:
            raise OperationalError(2013, "Lost connection to MySQL server during query")
      if DEBUG: dump_packet(recv_data)
      payload_buff.append(recv_data)
      bytes_to_read -= len(recv_data)
    self.__data = ''.join(payload_buff)

  def packet_number(self): return self.__packet_number

  def get_all_data(self): return self.__data

  def read(self, size):
    """Read the first 'size' bytes in packet and advance cursor past them."""
    result = self.peek(size)
    self.advance(size)
    return result

  def read_all(self):
    """Read all remaining data in the packet.

    (Subsequent read() or peek() will return errors.)
    """
    result = self.__data[self.__position:]
    self.__position = None  # ensure no subsequent read() or peek()
    return result

  def advance(self, length):
    """Advance the cursor in data buffer 'length' bytes."""
    new_position = self.__position + length
    if new_position < 0 or new_position > len(self.__data):
      raise Exception('Invalid advance amount (%s) for cursor.  '
                      'Position=%s' % (length, new_position))
    self.__position = new_position

  def rewind(self, position=0):
    """Set the position of the data buffer cursor to 'position'."""
    if position < 0 or position > len(self.__data):
      raise Exception("Invalid position to rewind cursor to: %s." % position)
    self.__position = position

  def peek(self, size):
    """Look at the first 'size' bytes in packet without moving cursor."""
    result = self.__data[self.__position:(self.__position+size)]
    if len(result) != size:
      error = ('Result length not requested length:\n'
               'Expected=%s.  Actual=%s.  Position: %s.  Data Length: %s'
               % (size, len(result), self.__position, len(self.__data)))
      if DEBUG:
        print error
        self.dump()
      raise AssertionError(error)
    return result

  def get_bytes(self, position, length=1):
    """Get 'length' bytes starting at 'position'.

    Position is start of payload (first four packet header bytes are not
    included) starting at index '0'.

    No error checking is done.  If requesting outside end of buffer
    an empty string (or string shorter than 'length') may be returned!
    """
    return self.__data[position:(position+length)]

  def read_coded_length(self):
    """Read a 'Length Coded' number from the data buffer.

    Length coded numbers can be anywhere from 1 to 9 bytes depending
    on the value of the first byte.
    """
    c = ord(self.read(1))
    if c == NULL_COLUMN:
      return None
    if c < UNSIGNED_CHAR_COLUMN:
      return c
    elif c == UNSIGNED_SHORT_COLUMN:
      return unpack_uint16(self.read(UNSIGNED_SHORT_LENGTH))
    elif c == UNSIGNED_INT24_COLUMN:
      return unpack_int24(self.read(UNSIGNED_INT24_LENGTH))
    elif c == UNSIGNED_INT64_COLUMN:
      # TODO: what was 'longlong'?  confirm it wasn't used?
      return unpack_int64(self.read(UNSIGNED_INT64_LENGTH))

  def read_length_coded_binary(self):
    """Read a 'Length Coded Binary' from the data buffer.

    A 'Length Coded Binary' consists first of a length coded
    (unsigned, positive) integer represented in 1-9 bytes followed by
    that many bytes of binary data.  (For example "cat" would be "3cat".)
    """
    length = self.read_coded_length()
    if length:
      return self.read(length)

  def is_ok_packet(self):
    return ord(self.get_bytes(0)) == 0

  def is_eof_packet(self):
    return ord(self.get_bytes(0)) == 254  # 'fe'

  def is_resultset_packet(self):
    field_count = ord(self.get_bytes(0))
    return field_count >= 1 and field_count <= 250

  def is_error_packet(self):
    return ord(self.get_bytes(0)) == 255

  def check_error(self):
    if self.is_error_packet():
      self.rewind()
      self.advance(1)  # field_count == error (we already know that)
      errno = unpack_uint16(self.read(2))
      if DEBUG: print "errno = %d" % errno
      raise_mysql_exception(self.__data)

  def dump(self):
    dump_packet(self.__data)


class FieldDescriptorPacket(MysqlPacket):
  """A MysqlPacket that represents a specific column's metadata in the result.

  Parsing is automatically done and the results are exported via public
  attributes on the class such as: db, table_name, name, length, type_code.
  """

  def __init__(self, *args):
    MysqlPacket.__init__(self, *args)
    self.__parse_field_descriptor()

  def __parse_field_descriptor(self):
    """Parse the 'Field Descriptor' (Metadata) packet.

    This is compatible with MySQL 4.1+ (not compatible with MySQL 4.0).
    """
    self.catalog = self.read_length_coded_binary()
    self.db = self.read_length_coded_binary()
    self.table_name = self.read_length_coded_binary()
    self.org_table = self.read_length_coded_binary()
    self.name = self.read_length_coded_binary()
    self.org_name = self.read_length_coded_binary()
    self.advance(1)  # non-null filler
    self.charsetnr = struct.unpack('<h', self.read(2))[0]
    self.length = struct.unpack('<i', self.read(4))[0]
    self.type_code = ord(self.read(1))
    flags = struct.unpack('<h', self.read(2))
    # TODO: what is going on here with this flag parsing???
    self.flags = int(("%02X" % flags)[1:], 16)
    self.scale = ord(self.read(1))  # "decimals"
    self.advance(2)  # filler (always 0x00)

    # 'default' is a length coded binary and is still in the buffer?
    # not used for normal result sets...

  def description(self):
    """Provides a 7-item tuple compatible with the Python PEP249 DB Spec."""
    desc = []
    desc.append(self.name)
    desc.append(self.type_code)
    desc.append(None) # TODO: display_length; should this be self.length?
    desc.append(self.get_column_length()) # 'internal_size'
    desc.append(self.get_column_length()) # 'precision'  # TODO: why!?!?
    desc.append(self.scale)

    # 'null_ok' -- can this be True/False rather than 1/0?
    #              if so just do:  desc.append(bool(self.flags % 2 == 0))
    if self.flags % 2 == 0:
      desc.append(1)
    else:
      desc.append(0)
    return tuple(desc)

  def get_column_length(self):
    if self.type_code == FIELD_TYPE.VAR_STRING:
      mblen = MBLENGTH.get(self.charsetnr, 1)
      return self.length // mblen
    return self.length

  def __str__(self):
    return ('%s %s.%s.%s, type=%s'
            % (self.__class__, self.db, self.table_name, self.name,
               self.type_code))


class Connection(object):
    """
    Representation of a socket with a mysql server.

    The proper way to get an instance of this class is to call
    connect()."""
    errorhandler = defaulterrorhandler

    def __init__(self, host="localhost", user=None, passwd="",
                 db=None, port=3306, unix_socket=None,
                 charset=DEFAULT_CHARSET, sql_mode=None,
                 read_default_file=None, conv=decoders, use_unicode=True,
                 client_flag=0, cursorclass=Cursor, init_command=None,
                 connect_timeout=None, ssl=None, read_default_group=None,
                 compress=None, named_pipe=None):
        """
        Establish a connection to the MySQL database. Accepts several
        arguments:

        host: Host where the database server is located
        user: Username to log in as
        passwd: Password to use.
        db: Database to use, None to not use a particular one.
        port: MySQL port to use, default is usually OK.
        unix_socket: Optionally, you can use a unix socket rather than TCP/IP.
        charset: Charset you want to use.
        sql_mode: Default SQL_MODE to use.
        read_default_file: Specifies  my.cnf file to read these parameters from under the [client] section.
        conv: Decoders dictionary to use instead of the default one. This is used to provide custom marshalling of types. See converters.
        use_unicode: Whether or not to default to unicode strings.
        client_flag: Custom flags to send to MySQL. Find potential values in constants.CLIENT.
        cursorclass: Custom cursor class to use.
        init_command: Initial SQL statement to run when connection is established.
        connect_timeout: Timeout before throwing an exception when connecting.
        ssl: A dict of arguments similar to mysql_ssl_set()'s parameters. For now the capath and cipher arguments are not supported.
        read_default_group: Not supported
        compress; Not supported
        named_pipe: Not supported
        """


        if read_default_group or compress or named_pipe:
            raise NotImplementedError, "read_default_group, compress and named_pipe arguments are not supported"

        if ssl and (ssl.has_key('capath') or ssl.has_key('cipher')):
            raise NotImplementedError, 'ssl options capath and cipher are not supported'

        if ssl and not have_ssl:
            raise RuntimeError, "missing ssl module"

        self.ssl = False
        if ssl:
            self.ssl = True
            client_flag |= SSL
            for k in ('key', 'cert', 'ca'):
                v = None
                if ssl.has_key(k):
                    v = ssl[k]
                setattr(self, k, v)

        if read_default_file:
            cfg = ConfigParser.RawConfigParser()
            cfg.read(os.path.expanduser(read_default_file))

            def _config(key, default):
                try:
                    return cfg.get("client",key)
                except:
                    return default
            
            user = _config("user",user)
            passwd = _config("password",passwd)
            host = _config("host", host)
            db = _config("db",db)
            unix_socket = _config("socket",unix_socket)
            port = _config("port", port)
            charset = _config("default-character-set", charset)
                
        self.host = host
        self.port = port
        self.user = user
        self.password = passwd
        self.db = db
        self.unix_socket = unix_socket
        self.use_unicode = use_unicode
        self.charset = DEFAULT_CHARSET

        client_flag |= CAPABILITIES
        client_flag |= MULTI_STATEMENTS
        if self.db:
            client_flag |= CONNECT_WITH_DB
        self.client_flag = client_flag

        self.cursorclass = cursorclass
        self.connect_timeout = connect_timeout
        
        self._connect()
        
        self.set_charset_set(charset)
        self.messages = []
        self.encoders = encoders
        self.decoders = conv
        self.field_decoders = field_decoders

        self._affected_rows = 0
        self.host_info = "Not connected"
        
        self.autocommit(False)
        
        if sql_mode is not None:
            c = self.cursor()
            c.execute("SET sql_mode=%s", (sql_mode,))

        self.commit()

        if init_command is not None:
            c = self.cursor()
            c.execute(init_command)
            
            self.commit()
        

    def close(self):
        ''' Send the quit message and close the socket '''
        try:
            send_data = struct.pack('<i',1) + COM_QUIT
            sock = self.socket
            sock.send(send_data)
            sock.close()
        except:
            exc,value,tb = sys.exc_info()
            self.errorhandler(None, exc, value)
    
    def autocommit(self, value):
        ''' Set whether or not to commit after every execute() '''
        try:
            self._execute_command(COM_QUERY, "SET AUTOCOMMIT = %s" % \
                                      self.escape(value))
            self.read_packet()
        except:
            exc,value,tb = sys.exc_info()
            self.errorhandler(None, exc, value)

    def commit(self):
        ''' Commit changes to stable storage '''
        try:
            self._execute_command(COM_QUERY, "COMMIT")
            self.read_packet()
        except:
            exc,value,tb = sys.exc_info()
            self.errorhandler(None, exc, value)

    def rollback(self):
        ''' Roll back the current transaction '''
        try:
            self._execute_command(COM_QUERY, "ROLLBACK")
            self.read_packet()
        except:
            exc,value,tb = sys.exc_info()
            self.errorhandler(None, exc, value)

    def escape(self, obj):
        ''' Escape whatever value you pass to it  '''
        return escape_item(obj, self.charset)

    def literal(self, obj):
        ''' Alias for escape() '''
        return escape_item(obj, self.charset)

    def cursor(self):
        ''' Create a new cursor to execute queries with '''
        return self.cursorclass(self)
    
    def __enter__(self):
        ''' Context manager that returns a Cursor '''
        return self.cursor()

    def __exit__(self, exc, value, traceback):
        ''' On successful exit, commit. On exception, rollback. '''
        if exc:
            self.rollback()
        else:
            self.commit()

    # The following methods are INTERNAL USE ONLY (called from Cursor)
    def query(self, sql):
        self._execute_command(COM_QUERY, sql)
        self._affected_rows = self._read_query_result()
        return self._affected_rows
    
    def next_result(self):
        self._affected_rows = self._read_query_result()
        return self._affected_rows

    def affected_rows(self):
        return self._affected_rows

    def kill(self, thread_id):
        arg = struct.pack('<I', thread_id)
        try:
            self._execute_command(COM_PROCESS_KILL, arg)
        except:
            exc,value,tb = sys.exc_info()
            self.errorhandler(None, exc, value)
            return
        pkt = self.read_packet()
        return pkt.is_ok_packet()
    
    def ping(self, reconnect=True):
        ''' Check if the server is alive '''
        try:
            self._execute_command(COM_PING, "")
        except:
            if reconnect:
                self._connect()
                return self.ping(False)
            else:
                exc,value,tb = sys.exc_info()
                self.errorhandler(None, exc, value)
                return

        pkt = self.read_packet()
        return pkt.is_ok_packet()

    def set_charset_set(self, charset):
        try:
            sock = self.socket
            if charset and self.charset != charset:
                self._execute_command(COM_QUERY, "SET NAMES %s" %
                                      self.escape(charset))
                self.read_packet()
                self.charset = charset     
        except:
            exc,value,tb = sys.exc_info()
            self.errorhandler(None, exc, value)

    def _connect(self):
        try:
            if self.unix_socket and (self.host == 'localhost' or self.host == '127.0.0.1'):
                sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
                t = sock.gettimeout()
                sock.settimeout(self.connect_timeout)
                sock.connect(self.unix_socket)
                sock.settimeout(t)
                self.host_info = "Localhost via UNIX socket"
                if DEBUG: print 'connected using unix_socket'
            else:
                sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
                t = sock.gettimeout()
                sock.settimeout(self.connect_timeout)
                sock.connect((self.host, self.port))
                sock.settimeout(t)
                self.host_info = "socket %s:%d" % (self.host, self.port)
                if DEBUG: print 'connected using socket'
            self.socket = sock
            self._get_server_information()
            self._request_authentication()
        except socket.error, e:
            raise OperationalError(2003, "Can't connect to MySQL server on %r (%d)" % (self.host, e.args[0]))
    
    def read_packet(self, packet_type=MysqlPacket):
      """Read an entire "mysql packet" in its entirety from the network
      and return a MysqlPacket type that represents the results."""

      # TODO: is socket.recv(small_number) significantly slower than
      #       socket.recv(large_number)?  if so, maybe we should buffer
      #       the socket.recv() (though that obviously makes memory management
      #       more complicated.
      packet = packet_type(self.socket)
      packet.check_error()
      return packet

    def _read_query_result(self):
        result = MySQLResult(self)
        result.read()
        self._result = result
        return result.affected_rows

    def _send_command(self, command, sql):
        send_data = struct.pack('<i', len(sql) + 1) + command + sql

        sock = self.socket
        sock.send(send_data)

        if DEBUG: dump_packet(send_data)

    def _execute_command(self, command, sql):
        self._send_command(command, sql)
        
    def _request_authentication(self):
        sock = self.socket
        self._send_authentication()

    def _send_authentication(self):
        sock = self.socket
        self.client_flag |= CAPABILITIES
        if self.server_version.startswith('5'):
            self.client_flag |= MULTI_RESULTS

        if self.user is None:
            raise ValueError, "Did not specify a username"
    
        data_init = (struct.pack('<i', self.client_flag)) \
                            + "\0\0\0\x01" + '\x08' + '\0'*23

        next_packet = 1

        if self.ssl:
            data = pack_int24(len(data_init)) + chr(next_packet) + data_init
            next_packet += 1

            if DEBUG: dump_packet(data)

            sock.send(data)
            sock = self.socket = ssl.wrap_socket(sock, keyfile=self.key,
                                           certfile=self.cert,
                                           ssl_version=ssl.PROTOCOL_TLSv1,
                                           cert_reqs=ssl.CERT_REQUIRED,
                                           ca_certs=self.ca)

        data = data_init + self.user+"\0" + _scramble(self.password, self.salt)

        if self.db:
            data += self.db.encode(self.charset) + "\0"

        data = pack_int24(len(data)) + chr(next_packet) + data
        next_packet += 2
        
        if DEBUG: dump_packet(data)
        
        sock.send(data)

        auth_packet = MysqlPacket(sock)
        auth_packet.check_error()
        if DEBUG: auth_packet.dump()

        # if old_passwords is enabled the packet will be 1 byte long and
        # have the octet 254

        if auth_packet.is_eof_packet():
            # send legacy handshake
            #raise NotImplementedError, "old_passwords are not supported. Check to see if mysqld was started with --old-passwords, if old-passwords=1 in a my.cnf file, or if there are some short hashes in your mysql.user table."
            data = _scramble_323(self.password, self.salt) + "\0"
            data = pack_int24(len(data)) + chr(next_packet) + data
        
            sock.send(data)
            auth_packet = MysqlPacket(sock)
            auth_packet.check_error()
            if DEBUG: auth_packet.dump()
        
        
    # _mysql support
    def thread_id(self):
        return self.server_thread_id[0]

    def character_set_name(self):
        return self.charset

    def get_host_info(self):
        return self.host_info
    
    def get_proto_info(self):
        return self.protocol_version
        
    def _get_server_information(self):
        sock = self.socket
        i = 0
        packet = MysqlPacket(sock)
        data = packet.get_all_data()

        if DEBUG: dump_packet(data)
        #packet_len = ord(data[i:i+1])
        #i += 4
        self.protocol_version = ord(data[i:i+1])
        
        i += 1
        server_end = data.find("\0", i)
        self.server_version = data[i:server_end]
        
        i = server_end + 1
        self.server_thread_id = struct.unpack('<h', data[i:i+2])

        i += 4
        self.salt = data[i:i+8]
        
        i += 9
        if len(data) >= i + 1:
            i += 1
       
        self.server_capabilities = struct.unpack('<h', data[i:i+2])[0]

        i += 1
        self.server_language = ord(data[i:i+1])
        
        i += 16 
        if len(data) >= i+12-1:
            rest_salt = data[i:i+12]
            self.salt += rest_salt

    def get_server_info(self):
        return self.server_version

    Warning = Warning
    Error = Error
    InterfaceError = InterfaceError
    DatabaseError = DatabaseError
    DataError = DataError
    OperationalError = OperationalError
    IntegrityError = IntegrityError
    InternalError = InternalError
    ProgrammingError = ProgrammingError
    NotSupportedError = NotSupportedError

# TODO: move OK and EOF packet parsing/logic into a proper subclass
#       of MysqlPacket like has been done with FieldDescriptorPacket.
class MySQLResult(object):

    def __init__(self, connection):
        from weakref import proxy
        self.connection = proxy(connection)
        self.affected_rows = None
        self.insert_id = None
        self.server_status = 0
        self.warning_count = 0
        self.message = None
        self.field_count = 0
        self.description = None
        self.rows = None
        self.has_next = None

    def read(self):
        self.first_packet = self.connection.read_packet()

        # TODO: use classes for different packet types?
        if self.first_packet.is_ok_packet():
            self._read_ok_packet()
        else:
            self._read_result_packet()

    def _read_ok_packet(self):
        self.first_packet.advance(1)  # field_count (always '0')
        self.affected_rows = self.first_packet.read_coded_length()
        self.insert_id = self.first_packet.read_coded_length()
        self.server_status = struct.unpack('<H', self.first_packet.read(2))[0]
        self.warning_count = struct.unpack('<H', self.first_packet.read(2))[0]
        self.message = self.first_packet.read_all()

    def _read_result_packet(self):
        self.field_count = ord(self.first_packet.read(1))
        self._get_descriptions()
        self._read_rowdata_packet()

    # TODO: implement this as an iteratable so that it is more
    #       memory efficient and lower-latency to client...
    def _read_rowdata_packet(self):
      """Read a rowdata packet for each data row in the result set."""
      rows = []
      while True:
        packet = self.connection.read_packet()
        if packet.is_eof_packet():
            self.warning_count = packet.read(2)
            server_status = struct.unpack('<h', packet.read(2))[0]
            self.has_next = (server_status
                             & SERVER_STATUS.SERVER_MORE_RESULTS_EXISTS)
            break

        row = []
        for field in self.fields:
            if field.type_code in self.connection.decoders:
                converter = self.connection.decoders[field.type_code]

                if DEBUG: print "DEBUG: field=%s, converter=%s" % (field, converter)
                data = packet.read_length_coded_binary()
                converted = None
                if data != None:
                    converted = converter(data)
            else:
                converter = self.connection.field_decoders[field.type_code]
                if DEBUG: print "DEBUG: field=%s, converter=%s" % (field, converter)
                data = packet.read_length_coded_binary()
                converted = None
                if data != None:
                    converted = converter(self.connection, field, data)

            row.append(converted)

        rows.append(tuple(row))

      self.affected_rows = len(rows)
      self.rows = tuple(rows)
      if DEBUG: self.rows

    def _get_descriptions(self):
        """Read a column descriptor packet for each column in the result."""
        self.fields = []
        description = []
        for i in xrange(self.field_count):
            field = self.connection.read_packet(FieldDescriptorPacket)
            self.fields.append(field)
            description.append(field.description())

        eof_packet = self.connection.read_packet()
        assert eof_packet.is_eof_packet(), 'Protocol error, expecting EOF'
        self.description = tuple(description)
